The invention relates in general to iron or wood type gold clubs.
While the description of the invention below relates more specifically to irons, it is nevertheless equally applicable to woods. It suffices that the strike face of the club, whether planar or slightly convex, is inclined relative to the ground.
For the sake of convenience and to facilitate the following description, FIG. 1 shows a golf club as oriented in use. The club is positioned in virtual manner in a system of mutually spatially orthogonal planes P1, P2, P3 (FIG. 1), wherein the shaft axis I-I' is located in the P1 plane, the P3 plane denotes the ground, and the P2 plane is orthogonal to the ground, passes through the axis of the strike zone and is orthogonal to the P1 plane. The club shaft forms an angle .beta., also called the "lie angle" relative to an axis Ox contained in the P3 plane.
FIGS. 2 through 4 show a prior art golf club, in this instance an iron. FIG. 2. shows a front view of the entire golf club. FIG. 3 and 4 show front and side views, respectively, of the head of the golf club.
Such an iron, denoted by the overall reference 1, essentially comprises a grip 3 affixed to a shaft 2 connected to the head 4 by a hosel 6, which receives the shaft 2 in a bore 5 thereof. More specifically, the bore 5 is inside the hosel 6 which is connected to a head 4 at the end of the heel 7 of the head.
The actual head 4, whether metallic, molded or forged, or of machined wood, comprises a front strike face 8 slanted at an angle .gamma. (FIG. 4) relative to an Oy axis contained in the P1 plane (FIG. 1). The angle is called the opening or "loft" angle. The strike face 8 comprises a grooved striking zone 9 which is bounded at its base by a lower, leading edge 11 and at its top by an upper edge 12. The upper edge 12 slopes when projected onto the plane P1 by an angle .alpha. (FIG. 3) relative to the axis Ox defining the ground.
The grip 3 and shaft 2 define a longitudinal axis I-I' along which is located the bore 5 connecting the shaft 2 to the hosel 6. The sloping front strike face 8 comprises two side zones 7 and 10 on either side of the grooved striking zone 9. The wide free end zone 10 is adjacent the toe of the club head, and the opposite narrow zone connected to the shaft includes a connection segment 13 between the striking zone 9 and the hosel 6. This smooth connection segment 13 ends in the heel 7 and is linked to the hosel 6. Accordingly the hosel 6 comprises two main parts: a connection segment 13, at the heel 7, which as a rule will be tangential to and at the end of the heel, and a straight end comprising a bore 5 to connect the shaft 2 to the club head.
Heretofore, the hosel 6 as a rule has been aligned with the shaft 2 along the longitudinal axis I-I' and, as already mentioned, is located at the end of the heel 7, that is, at the most narrow end of the front strike face 8. More specifically, the hosel is connected to the head 4 at the heel 7 of the smooth connection segment 13.
It is known that at the time of impact between the head 4 and a golf ball, the shock generates a torsion and vibrations propagate along the shaft 2 as far as the grip 3. In the first place there is discomfort, and then player fatigue, which may go as far as trauma to the arm.
U.S. Pat. No. 4,986,541 describes more easily played irons for average or relatively inexperienced players. This patent proposes a relationship to vary the "face progression", that is, seen in profile, the distance between the longitudinal grip axis I-I' and the most advanced point of the lower edge 11 of the head 4. It is known that the more the axis I-I' is behind the lower edge 11, the more the ball tends to rise. This makes it difficult to use long irons, that is, irons with shallow sloping angles .gamma. for their strike faces, for instance angles .gamma. between ten and twenty degrees. To achieve this offset of the "face progression", the irons made according to the disclosure of U.S. Pat. No. 4,986,541 include a hosel which is offset in the plane P2.
However in all the embodiments of U.S. Pat. No. 4,986,541, the connection segment 13 of the hosel 6, is tangential to the most narrow end of the head 4. In other words, the connection segment 13 coincides with the heel 7. As a result, the connection segment 13 is comparatively far from the striking zone 9, hence from the ideal center of impact with a golf ball. During impact, therefore, there still is a substantial torque.
British Patent 2,109,249 describes a golf club of which the shaft joins the hosel of the club head by means of an elbow and a fitting. In this design the shaft can be pointed in a given direction so it may be possible to change the head positions relative to the shaft as needed. Unfortunately, when the shaft is angularly offset inside the fitting, all the relative parameters also will change, and this club, which moreover is costly and fragile, is inconvenient in practice.
U.S. Pat. No. 3,966,210 describes a club, in particular a putter, of which the shaft joins the head by a hosel substantially back from the strike face. This design is applicable to the putter clubs or to so-called "woods", but not to irons, especially those with a wide loft angle, because it is technically impossible to arrange the shaft at the back of the head.
Other prior art golf clubs also include so-called "perimeter weighting" means to make the clubs more easily used by inexperienced players. For example, FIG. 8 shows a golf club head as disclosed in U.S. Pat. No. 4,621,813, which employs redistributed perimeter weighting on the back surface of the club to improve resistance to twisting of the club head upon off-center impacts with a golf ball. However, the perimeter weighting is redistributed and concentrated only at the lower edge heel and toe portions of the club back surface, and no redistribution of the perimeter weighting is provided on the top edge of the club. Nor is there any disclosure or recognition in the art of the importance of redistributing the perimeter weighting at the top edge of the club.